Why Xen Project?

The Xen Project team is a global open source community that develops the Xen Project Hypervisor and its associated subprojects. Xen (pronounced /’zɛn/) Project has its origins in the ancient greek term Xenos (ξένος), which can be used to refer to guest-friends whose relationship is constructed under the ritual of xenia ("guest-friendship"), which in term is a wordplay on the idea of guest operating systems as well as a community of developers and users. The original website was created in 2003 to allow a global community of developers to contribute and improve the hypervisor. Click on the link to find more about the projects’s interesting history.

The community supporting the project follows a number of principles: Openess, Transparency, Meritocracy and Consensus Decision Making. Find out more about how the community governs itself.

What Differentiates the Xen Project Community?

In any Open Source effort, the community makes the difference -- and the Xen Project community is a jewel! Our community is both active and growing. 2015's 4.6 release had more new features than any release in a decade! Some project communities lose steam after a decade; ours is actually becoming more diverse, with more and more organizations stepping in to help build new features. Innovation is not slowing down -- it is accelerating! In the age of the cloud, the hypervisor needs to be opening doors to new experiences. The cloud is not static; your hypervisor cannot afford to be static either. It should be unlocking new possibilities to enable the next generation of the cloud. That's precisely what we are doing at Xen Project.

What Differentiates the Xen Project Software?

There are several virtualization technologies available in the world today. Our Xen Project virtualization and cloud software includes many powerful features which make it an excellent choice for many organizations:

A virtualization technology which only supports a few guest operating systems essentially locks the organization into those choices for years to come. With our hypervisor, you have the flexibility to use what you need and add other operating system platforms as your needs dictate. You are in control.

Supports multiple Cloud platforms: CloudStack, OpenStack

A virtualization technology which only supports one Cloud technology locks you into that technology. With the world of the Cloud moving so quickly, it could be a mistake to commit to one Cloud platform too soon. Our software keeps your choices open as Cloud solutions continue to improve and mature.

Reliable technology with a solid track record

The hypervisor has been in production for many years and is the #1 Open Source hypervisor according to analysts such as Gartner. Conservative estimates show that Xen has an active user base of 10+ million: these are users, not merely hypervisor installations which are an order of magnitude higher. Amazon Web Services alone runs ½ million virtualized Xen Project instances according to a recent study and other cloud providers such as Rackspace and hosting companies use the hypervisor at extremely large scale. Companies such as Google and Yahoo use the hypervisor at scale for their internal infrastructure. Our software is the basis of successful commercial products such as Citrix XenServer and Oracle VM, which support an ecosystem of more than 2000 commercially certified partners today. It is clear that many major industry players regard our software as a safe virtualization platform for even the largest clouds.

Scalability

The hypervisor can scale up to 4,095 host CPUs with 16Tb of RAM. Using Para Virtualization (PV), the hypervisor supports a maximum of 512 VCPUs with 512Gb RAM per guest. Using Hardware Virtualization (HVM), it supports a maximum of 128 VCPUs with 1Tb RAM per guest.

Security is one of the major concerns when moving critical services to virtualization or cloud computing environments. The hypervisor provides a high level of security due to its modular architecture, which separates the hypervisor from the control and guest operating systems. The hypervisor itself is thin and thus provides a minimal attack surface. The software also contains the Xen Security Modules (XSM), which have been developed and contributed to the project by the NSA for ultra secure use-cases. XSM introduces control policy providing fine-grained controls over its domains and their interaction amongst themselves and the outside world. And, of course, it is also possible to use the hypervisor with SELinux. In addition, Xen’s Virtual Machine Introspection (VMI) subsystems make it the best hypervisor for security applications. For more information, see Virtual Machine Introspection with Xen and VM Introspection: Practical Applications.

The Xen Project also has a dedicated security team, which handles security vulnerabilities in accordance with our Security Policy. Unlike almost all corporations and even most open source projects, the Xen Project properly discloses, via an advisory, every vulnerability discovered in supported configurations. We also often publish advisories about vulnerabilities in other relevant projects, such as Linux and QEMU.

Flexibility

Our hypervisor is the most flexible hypervisor on the market, enabling you to tailor your installation to your needs. There are lots of choices and trade-offs that you can make. For example: the hypervisor works on older hardware using paravirtualization, on newer hardware using HVM or PV on HVM. Users can choose from three tool stacks (XL, XAPI & LIBVIRT), from an ecosystem of software complementing the project and choose the most suitable flavour of Linux and Unix operating system for their needs. Further, the project's flexible architecture enables vendors to create Xen-based products and services for servers, cloud, desktop in particular for ultra secure environments.

Modularity

Our architecture is uniquely modular, enabling a degree of scalability, robustness, and security suitable even for large, critical, and extremely secure environments. The control functionality in our control domain can be divided into small modular domains running a minimal kernel and a driver, control logic or other functionality: we call this approach Domain Disaggregation. Disaggregated domains are conceptually similar to processes in an operating system. They can be started/ended on demand, without affecting the rest of the system. Disaggregated domains reduce attack surface and distribute bottlenecks. It enables you to restart an unresponsive device driver without affecting your VMs.

VM Migration

The software supports Virtual Machine Migration. This allows you to react to changing loads on your servers, protecting your workloads.

Open Source

Open Source means that you have influence over the direction of the code. You are not at the mercy of some immovable external organization which may have priorities which do not align with your organization. You can participate and help ensure that your needs are heard in the process. And you never have to worry that some entity has decided to terminate the product for business reasons. An Open Source project will live as long as there are parties interested in advancing the software.

Multi-vendor support

The project enjoys support from a number of major software and service vendors. This gives end-users numerous places to find support, as well as numerous service providers to work with. With such a rich commercial ecosystem around the project, there is plenty of interest in keeping the project moving forward to ever greater heights.

Xen Project Ecosystem and Users

The project sports a large ecosystem of hosting and cloud vendors, small users, and research institutions. They continue to produce tools interfacing with our code, as well as Open Source projects and commercial products that have been built on top of, or interface with, our software. If you want to find out more, go to the Ecosystem Directory. We do not know exactly how big our user base is, as our software gets distributed by third parties, Linux distributions, etc. However, from the data we have we know that our user base is in the tens of millions individuals and organizations that use solutions involving Xen Project software.